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Prototypes and performance

Full-scale prototype of part of a typical office floor for its proposed 16-storey speculative tower for Derwent

Prototypes, either scale models or full-sized, are increasingly used to test and predict building performance, rather than simply to test ideas, says Hattie Hartman

Prototypes in architecture are nothing new. Until recently, they have been used primarily to test and refine elements of buildings, generally during construction and have been driven by aesthetics. This means that the margin for manoeuvre - the ability to change one’s mind after a reality check - is severely limited. Practices ranging from Foster + Partners to Berlin-based Barkow Leibinger increasingly build prototypes earlier in the design process, not only to test ideas, but to enhance environmental performance and reduce risk. Reduced risk translates into reduced costs.

At its City Road project for Derwent in London, AHMM has built a 178m² office suite prototype on stilts as a challenge to the commercial spec office market. ‘We are trapped in existing models,’ director Simon Allford observes. ‘The British Council for Office’s (BCO) bottom line benchmarks are dragging everything down.’

He refers to the perched box just off Old Street roundabout as a ‘working prototype, not a show suite’, although the 10m-diameter beach ball perched on top, representing a tonne of carbon (equal to two days’ savings compared to a conventional Part L office) reeks of marketing. It is, nevertheless, a clever ploy given the area’s visual cacophony.

Full-scale prototype of part of a typical office floor for its proposed 16-storey speculative tower for Derwent

The proposed 16-storey tower will be naturally ventilated at the perimeter. The ventilated portion accounts for 70 per cent of the 45m² floor plate. Generous ceiling heights are set at 3.5m, and openable windows will be screened by punched metal panels, creating dappled light and enabling air flow.

By removing all the unnecessary kit, rather than designing for the worst-case scenarios of a few days a year, the building is lean, costed at £500/m².

Arup will monitor the City Road prototype for a 12-month period before the project starts on site. ‘This is the first time we have a working model we can look at and measure, so that we can make changes if needed,’ says Arup’s Michael Stych. The building can operate almost entirely passively. The key is what the design team has dubbed ‘CCC’ (as opposed to AC), standing for ‘concrete core cooling’. Water pipes embedded in the floor slabs provide coolth when needed and the entire system will be linked to an online user interface for occupants to access.

Foster + Partners has several major projects with prototypes under way, including a 17m-tall, 1:5 scale model of one of the pods for the Zayed National Museum in Abu Dhabi and at its South Beach project in Singapore. At South Beach, the prototype was used to test glass types to achieve optimum visual light transmission, reflectivity and reduce glare. Different louvre spacings were also trialed for lightness of appearance and to test daylight levels under the canopy.

Fosters prototype at South Beach

Speaking of the practice’s work at Masdar, Foster + Partners’ Gerard Evenden says: ‘Prototyping was essential, not just for the aesthetics, but to understand how the building would be put together. To reduce energy consumption, the connections are a key design challenge.’

At Masdar, prototypes of both student accommodation and a laboratory building were constructed, including a box behind to simulate a room. This enabled studies of light and glare at different times of day to ensure appropriate levels. Evenden emphasises that the contractor’s price was lower because the prototype clarified exactly what was to be built and the construction sequencing.

KieranTimberlake, the Philadelphia-based architect of London’s new American Embassy, has a strong culture of prototyping, which it uses variously to test, develop ideas and innovate. Speaking at a recent conference on prototyping, organised by the Building Centre and the University of Nottingham, James Timberlake highlighted the importance of measuring, data verification and monitoring as ‘tools in the architects’ quiver’, arguing that sustainability must be actually measured, and that prototypes are central to this process. The practice now uses sensors to send real time performance data to smart phones and computers, not only from prototypes, but also from buildings adjacent to a proposed site, enabling the use of energy models based on accurate microclimatic conditions.

Barkow Liebinger’s Smart Material House, Hamburg

Awarded a Global Holcim Innovation prize last year by the Holcim Foundation for Sustainable Construction, Barkow Leibinger spent the prize money on building a 1:1 prototype of a typical wall panel for its proposed Smart Material House in Hamburg. The 400mm-thick, self-insulating concrete wall panel uses recycled foam glass aggregate. The Hamburg project did not proceed but the architect hopes to replicate this same technique for infill housing on a vacant site near the former Berlin Wall.

A new initiative within academia and industry mirrors this increased interest in prototypes as a tool for innovation. The Architectural Association in conjunction with RMIT University Melbourne has launched an international research platform to work with industry to develop prototypes focused on the transformation of existing buildings in Europe and rapid construction in Australia. Four six-month fellowships will be offered this year (details: www.independentsgroup.net; deadline for applications June 28). Research areas range from the implementation of new survey techniques, which enable better understanding of building performance, to exploration of new materials to enhance the performance of existing building fabric.The value of prototypes to better inform the environmental impact of projects is undisputed. The challenge is to convince clients to pay for them up-front. Only then can the real lessons be learned.

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